In recent years, compactness, high output, and high quality have been required in rotary electric machines that are used as electric motors or generators. In high-output rotary electric machines of this kind, since high voltages are applied, electric potential differences that arise between coils that are mounted into an armature core have increased, and it has become necessary to have thicknesses of insulating material that can bear them. However, if the thickness of the insulating material is increased without changing the shape of the armature core, then coil space is reduced by an amount proportionate to the increase in the thickness of the insulating material, reducing efficiency of the rotary electric machine. If the thickness of the insulating material is increased without changing the coil space, then the diameter of the armature core is increased by an amount proportionate to the increase in the thickness of the insulating material, leading to increases in the size of the rotary electric machine.
In consideration of such conditions, various methods have been proposed to suppress the electric potential differences that arise between the coils.
In conventional rotary electric machines such as that described in Patent Literature 1, for example, revolution coils that are near terminals in respective phase coils are accommodated in slots that are not adjacent to slots in which other phase coils are accommodated, and revolution coils that are nearer to neutral points than revolution coils that are accommodated at positions that are circumferentially adjacent to the revolution coils that are near the terminals in slots that are adjacent to those slots are accommodated at positions in the slots in which the revolution coils that are near the terminals are accommodated that are radially adjacent to the revolution coils that are near the terminals. Electric potential differences that arise between the revolution coils in the coil ends are suppressed thereby.
In conventional rotary electric machines such as that described in Patent Literature 2, in a stator winding that is formed by wye-connecting respective phase windings that are formed by connecting in series a plurality of distributed-winding and lap-wound coils, respective phase windings are disposed such that a first coil that is connected to an input terminal, a final coil that is connected to a neutral point, and a plurality of intermediate coils are each arranged in a single row circumferentially so as to have different radial positions in each of the phases, two intermediate coils among the plurality of intermediate coils in each of the phases are disposed to be positioned on two circumferential sides of the same-phase first coil, and the first coil of each of the phases is radially adjacent to an intermediate coil of another phase or a final coil of another phase that is connected electrically nearer to an intermediate point than the two adjacent same-phase intermediate coils. Shared voltages between same-phase and inter-phase adjacent coils are thereby relieved.